1. Field of the Invention
This invention relates to evaporative coolers and more particularly to a trap device for use with the sump drain of an evaporative cooler which prevents high velocity inflow of sewer gasses, and/or other contaminating materials from being drawn through the sump drain into the evaporative cooler during operation thereof.
2. Description of the Prior Art
As is well known in the art, an evaporative cooler is a mechanism which is used to cool relatively warm dry ambient air by the evaporation principle and direct the cooled air into a home, business establishment or other point of use. A typical evaporative cooler includes a cabinet structure having at least one porous wettable pad through which the ambient air is drawn into the cabinet. An air handling device, such as a fan or centrifugal blower assembly, is mounted in the cabinet to produce a negative static pressure therein, which draws the air through the wettable pad, and directs the cooled air to the point of use. The cabinet structure includes a pan-shaped bottom which serves as a sump, or reservoir, for containment of a water supply which is used to wet the porous pad. A pump is provided in the sump for supplying water to a distribution plumbing system provided in the cabinet, and the plumbing system directs the water onto the top of the porous pad or pads. The water delivered to the pad passes downwardly therethrough under the influence of gravity, and that which is not lost because of evaporation, returns to the sump for recirculation. A water supply device, usually in the form of a float controlled shut off valve, is provided to initially fill the sump and replace that which is lost as a result of evaporation.
The pan-shaped sump is provided with a standpipe which has its open upper end above the normal water level of the sump and has its open lower end extending through the bottom of the sump. The standpipe is provided for overflow protection to drain excess water from the sump in the event of sticking of the water supply device and the like, and for other water draining purposes as will now be explained.
As a result of evaporation and the entry of contaminating matter into the cooler, the water supply becomes contaminated and most manufactures recommend that a bleed-off system be used. A bleed-off system is used to continuously bleed-off a relatively small amount of contaminated water to allow the water supply device to replace the bled-off water with fresh water. Such a bleed-off system usually includes a special fitting that is mounted in the water outlet line leading from the pump to the cooler's distribution plumbing system. The fitting has a restricted outlet to keep the amount of bled-off water relatively low, and the bled-off contaminated water is directed via a bleed-off tube to the standpipe for draining purposes.
As a result of the above described water draining functions of the standpipe, it is a common practice to provide a drain hose or pipe for conducting water from the lower end of the standpipe to a suitable disposal point. In that a drain hose or pipe, is not standard equipment provided by a cooler manufacturer, but is instead something that is provided by an installer or owner, the drain hose or pipe may be configured in various ways.
In most instances, evaporative coolers are mounted on the roof of a building that is to be cooled, and in most cases the drain hose, or pipe will conduct drain water from the cooler to a plumbing vent pipe of the type commonly found on building roofs and thereby dispose of the drain water in the building's sewer line. In other instances, the drain hose, or pipe will be configured to direct the drain water onto the ground adjacent the building. Even though it is undesirable, some coolers do not have bleed-off systems and in such cases, sometime the cooler's are installed without any drain hose or pipe.
The problem associated with the standpipes provided in the sumps of evaporative coolers is that an extremely high velocity inflow of sewer gasses, or other contaminants, as determined by the drain hose, or pipe used, will be sucked into the cooler through the drain and standpipe, due to the negative static pressure in the cooler whenever it is operating.
Of primary concern is the sucking of sewer gasses into the cooler in instances where the drain hose, or pipe, is configured to deposit drain water in the sewer system via the plumbing vent pipe. In cases where the drain hose, or pipe, is configured to deposit the drain water onto the ground, mosquitos and the bacteria associated with stagnant standing water can similarly be drawn into the cooler. In cases where no drain hose or pipe is provided, insects and anything else in the area of the lower open end of the standpipe can be sucked into the cooler.
To the best of my knowledge, no device has been devised or suggested which closes the standpipe of an evaporative cooler against high velocity inflow into the cooler of sewer gasses or other contaminants and yet does not block or otherwise hamper the normal water draining functions of the cooler's of the cooler's standpipe.